In applications such as valves, valve components and tubular products for use in oil extraction applications, it is necessary to have an alloy characterized by a combination of high strength and corrosion resistance. More specifically, the alloy must have corrosion resistance in the presence of corrosive media such as sodium chloride, hydrogen sulfide and carbon dioxide.
Nickel-base alloys heretofor used in these applications are disclosed in U.S. Pat. Nos. 3,165,000 and 3,046,108. Although the nickel-base alloys of these patents have useful combinations of mechanical properties and corrosion resistance, they are deficient in that neither of these properties in combination is sufficient for the above mentioned oil-extraction applications. In addition to having a combination of high strength and corrosion resistance, the alloy must also be characterized by fabricability so that it may be fabricated to the desired component configurations, such as valves, valve components and tubular shapes. The necessary strength in alloys having sufficient corrosion resistance may be obtained with the conventional alloy designed as UNS-NO6625 by cold working. This alloy, however, is difficult to fabricate and specifically cracking is encountered during fabrication. Age-hardenable alloys, such as UNS-NO7718, which may be heat treated to the required strength levels, do not have sufficient corrosion resistance for the more severe corrosion environments encountered in oil extraction applications.